Rates of colon cancer have doubled among young people, and doctors still don’t know why

Early detection is key, experts say, in treating colon and rectal cancers. Getty

While rates of colorectal cancer are down in adults over 55, a recent study found that more young people are now being diagnosed with the disease.

According to findings published in the Journal of the National Cancer Institute, rates of colon cancer have doubled in U.S. adults aged 20-39 since the mid-1980s. In adults between the ages of 40 and 54, incidents of colon cancer have increased from 0.5 per cent to 1.3 per cent since the mid-1990s.

“The cause for the rise in young adults is unknown and a growing area of research,” Dr. Rebecca Siegel, the study’s lead author and a scientific director at the American Cancer Society, told Global News.

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“The obesity epidemic has probably contributed but does not appear to completely explain the trend.”

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When it comes to rectal cancer, the disease has been increasing “longer and faster” in adults aged 20-29 years old. The study, which analyzed the data of nearly 500,000 people, found rectal cancer rates increased 3.2 per cent annually from 1974 to 2013.

In Canada, health-care professionals are noticing a similar trend.

What’s causing the increase?

“What we’re seeing in Canadians under the age of 50 [is that] rates of colorectal cancer are increasing,” said Dr. Leah Smith, senior manager of surveillance at the Canadian Cancer Society.

“Overall, colorectal cancer rates are decreasing, but this decrease seems to be restricted to older age groups… There’s more research that needs to be done to investigate this increase as we’re not entirely clear yet what is causing it.”

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As Siegel pointed out, the rise in obesity rates in North America may be a contributing factor to colorectal cancer in younger adults.

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“We know that excess body weight is a major risk factor for colorectal cancer,” Smith said. “Rates of obesity are increasing in our population so that could explain the increase.”

A sedentary lifestyle may also up one’s risk, Smith said, just like a diet high in red or processed meat, alcohol or tobacco can.

There have also been changes in diagnostic care that may play a role, but experts are unsure of how much.

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“More use of colonoscopy in young adults may contribute to the rise, although it is probably not a big factor because … the largest increase has been for advanced stage disease, whereas screen-detected prevalent cancers are typically diagnosed at a localized stage,” Siegel explained.

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Despite the increase in rates, colorectal cancer is still primarily a disease that affects older adults, Smith says.

“About six per cent of all colorectal cancer cases occur under the age of 50, meaning … the bulk of colorectal cancer cases in Canada are occurring in older populations,” she explained.

How can Canadians help protect themselves?

Smith and Siegel both say that someone’s risk of developing colorectal cancer can be reduced by healthy lifestyle habits. These include being physically active, maintaining a healthy body weight, limiting red and processed meat consumption and avoiding large amounts of alcohol.

Smith also says that smoking increases your risk of colorectal cancer so avoiding tobacco is best.

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Screening for colon and rectal cancers is also important. Smith says there are screening programs in place for adults over 50 but adds that anybody who is experiencing symptoms that indicate colorectal cancer should be checked for it.

“Some of the signs of colorectal cancer are things like changes in bowel moments, blood in the stool, stomach cramping and weight loss,” Smith said.

Early detection is key as colorectal cancer is the second most diagnosed cancer in Canada and the second leading cause of cancer death. If it’s caught at Stage 1, it has a 90 per cent survival rate. If it’s caught at Stage 4, the survival rate is less than 15 per cent.

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“It’s always important we are aware of our body and are communicating openly and honestly with our health-care providers about what’s going on,” Smith said.

—With a file from Leslie Young

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